Indicator



H. HuRvl-rz June 2s, 1949.

INDICATOR www IN V EN TOR.

Patented June 28, 1949 UNITED STATES PATENT OFFICE INDICATOR Hyman Hurvitz, Washington, D. C.

Application May 20, 1948, Serial No. 28,222

8 Claims.

This inventionrelates generally to cathode ray tubes circuits and particularly to arrangements for regenerating and retaining on the faces of cathode ray tubes, images there created by means of signals which maybe of a transient nature.

' It is an object of thefinvention to provide arrangements for regenerating images on the face of a cathode tube indicator.

It isa further object of the invention to provide arrangements responsive to the presence of an indication on the face of a cathode vray tube indicator for feeding to that indicator signals tending to regenerate the indication.-

It is still another object of the invention to provide circuits of illumination responsive nature for scanning the face of a cathode ray tube ine dicator and for providing intensifying signalsl to the intensity grid of the indicator in response to the traverse by the scanning means of images on lthe face of the indicator;

It is still affurther object of the invention to provide a system for Vtransferring a visual image from one cathode ray tube indicator to another without interfering with the operation of the one cathode ray tube.

It is additionally an object of this invention tov provide a system for transferring visual indications among a plurality of cathode lray tube indi-` cators, and from one to another of the indicators, without interfering with lthe normal op'ration of the indicators in translating electrical signals into visual images.

Briefly described, the present invention in volves a cathode ray tube indicator on the face of which is generated visual images, byintensity modulation of the cathode ray beam of the indicator. In one specific application of the invention, the face of the indicatormay be scanned.v by applying to its beam deection electrodes signals derived from a plan position indication scanninggenerator of conventional type, the generator forming part of a, radar indicating system, and the indicator providing indications on its face of the ranges and bearings of remote targets. An image of the face of the indicator may be im*-v pressed by means of suitable lenses on the face of an iconoscope or image orthicon, having alight sensitive mosaic. The mosaic may be scanned by means of a cathode ray beam in known man:- ner, the scanning taking place in synchronism with the scanning at the cathode ray tube indicator'.

The output-electrode of vthe iconoscope or image orthicon may be connected to" the intensifier gridf oi the cathode iaytube indicator, in an intensity increasing relation. This connection may be made over an amplifier which may serve the pur-- pose of isolating the source o f normal signals applied to the grid of the cathode ray tube indicator from those regeneratively fed back from the iconoscope or imagey orthicon. By adjusting the gain of the amplifier an 4image originally produced on the face of the cathode ray tube indicator by an incoming signal may be intensied in response to the output o f the regenerating circuit, or its decay may be delayed in accordance with the adjustment of the gain of the amplifier. In order to assure that the transient ashes or clutter on the cathode ray tube indicator are not intensified in the same manner as desired signals a low level limiter may be connected in circuit with the amplifier, which eliminates all fedback signals which are of lessthan of a certain predetermined amplitude. Additionally an upper limiting circuit may be inserted in series with the amplifier to preventfeeding back of signals of greater than a, predetermined intensity, which might cause undue intensification of images on the face of the cathode ray tube indicator.

In accordance with a modification of the present invention, displays presented on the faces of cathode ray tube indicators may be transferred from one to another of such indicators, andthe transferred traces may be retained indefinitely on the other of the indicators, While the trace on the original cathode ray tube indicator is permitted to decay at its normal decay rate.

More specifically, in a radar system utilizing two radar equipments oi complementary character, such as one which is adapted for air survey at low angles, and one whichv is adapted for air survey at high angles, or alternatively one which is adapted for long range operation, and one which adapted for short range operation, and each employing a P. P. I.- type of presentation, signals from either of the P.- P. I. indicators may be transferred to the other of the indicators and the total display on either of the indicators may be retained indefinitely, or permitted to decay at any desired rate.

Fer a more detailed expianannn o fktiie pres-ent invention rference is made to thefolloiiviiigspec'-vification which may be" taken iri conjunction the accompanying drawings; wherein:

Figure 1 represents i-ri cnveitinal-'Zed iiin'c'- tional block diagram, a soe'cic embodiment off the invention as applid toa radar' system, and

Figi-ire 2y represents in conventional-ized initio@` tional block diagram a further radar systemlitili-zing my invention.

Referring now to Figure 1 of the drawings, an antenna I is provided which is rotated continuously by means of a motor 2, enabling the antenna I to scan continually all azimuthal directions surrounding its location. The antenna I is connected over a TR box 3, as is well understood in the art, it serving to protect the radar reeciver 5 from direct transmissions originating in the transmitter l by short circuiting the input circuit of receiver 5 in response to each pulse transmission, the short circuit being eliminated upon termination of the transmitted radar pulse. A pulse of radiant energy is emitted by antenna I in response to each pulse provided by the transmitter 6, these pulses traveling at the speed of light to remote objects, and being reflected or scattered thereby, some of the energy returns to the antenna E. Energy which returns to the antenna I is applied to the radar receiver 5 and ampliled and detected, the detected signal being applied to a grid of a cathode ray tube indicator 'I in such sense as to intensify the beam of the indicator l. A linkage between the antenna I and the P. P. I. scanning generator 8 is conventionally indicated by the dotted line 9, which may represent a mechanical linkage, or a linkage by means of a Selsyn system. The linkage serves to impose or impress upon the P. P. I. scanning generator 8 a measure of the instantaneous direction or azimuth of the antenna l. There is likewise impressed on the P. P. I. scanning generator 8 signals derived from the radar pulse transmitter 4 and impressed on the generator 8 over a line Il. The signals applied to the generator 8 over line I il serve to initiate radial scan of the beam of the indicator radial scanning taking place at a rate adequate to enable measurement of transmission time of pulses transmitted by the antenna I, and received thereby after scattering or deflection from remote objects. The linkage 9, on the other hand, serves to modulate the output of the scanning generator 8 to effect proper angular positioning of the beam of the indicator 'I, which is maintained by the linkage 9 at all times in correspondence with the azimuthal bearing of the antenna I.

The beam of the indicator I is normally cut off, and in response to received signals, detected by the receiver 5 and applied to the grid 6, the intensity of the cathode ray beam is increased, providing a luminous spot on the face of the indicator at a radial position corresponding with range of a remote object and at an angular position corresponding with the angular bearing of antenna I, at the times of signal reception. Thereby there is created on the face of the indicator 1 a so-called P. P. I. plot of remote obu jects surrounding the antenna I. The plot may consist of single spots on the face of the indicator, corresponding with remote aircraft or vessels, or it may consist of a plot showing the outline of large land masses, or the like.

The system as so far described is completely conventional and is, per se, not my invention.

Positioned in optical relation to the cathode ray tube indicator 'I is an iconoscope or image orthicon 20 having a cathode 2|, deflection electrodes 22, and an output electrode which comprises a light sensitive mosaic surface 23. Since the character and mode of operation of the iconoscope or image orthicon is well known, per se, in the pertinent art, no detailed explanation thereof is provided. Associated with the iconoscope or image orthicon 2l] is a lens system 24 a spot on the face of the indicator l,

which serves to focus on the mosaic surface 23 of the iconoscope or image orthicon 26 the image provided by the face of the cathode ray tube indicator l, there being a one to one correspondence between points of the face of the cathode ray tube indicator 1 and of the face of the mosaic 23 of the iconoscope or image orthicon. The output of the P. P. I. scanning generator 8 may be applied to the scanning electrodes 22 of the iconoscope or image orthicon 2l] to cause the latter to scan in precise synchronism with the scanning of the beam of the cathode ray tube indicator 1.

The output electrode or mosaic 23 of the iconoscope or image orthicon 2U is connected over a limiter 30 which passes only signals having intensities greater than a predetermined value, to an amplifier 3|, the gain of Which may be manually controlled. At the output of the amplier 3| is connected an upper level limiter or maximum output limiter 32, which cuts off signals having greater than a given predetermined amplitude. Both the lower and upper limiters 30 and 32 may be manually adjustable, if desired, to enable modication of the limits between which signals are transmitted. The output of the limiter 32 is applied in intensifying relation to grid 6 of the indicator '1.

Turning now to the operation of the system, images present on the face of the indicator I are impressed on the light sensitive mosaic surface of the iconoscope or image orthicon 20, each spot or lighted portion of the surface I being duplicated on the light sensitive surface of the tube 2t. As the beam of the tube 20 is caused to scan over the mosaic surface, signals are developed in the output electrode 23 which are impressed on the grid 6 of the tube 'I. Accordingly, if an image is once produced on the face of the tube I in response to a transient voltage applied to the grid 6, the light so created will produce a voltage at the output electrode 23 which is fed back to the grid 6 each time that the scanning beam of the iconoscope or image orthicon 20 passes over the position corresponding with that spot. The spot, accordingly, is continually regenerated, whether or not signals continue incoming at the receiver 6, provided, however, that the persistence of the screen of the indicator I is greater than the total time required for a single scanning cycle.

By suitable adjustments of the limiters 30 and 32, and of the gain of the amplifier 3|, an image once created on the face of the indicator I may be caused to increase in amplitude, to decay slowly, or to retain its brilliance, ISo if we imagine a single spot to have been created on the face of the indicator 1 in response to a given voltage or a voltage of a given magnitude, if the regeneration circuit or amplier 3| is so set as to feed back to the grid 6 a voltage of that same amplitude in response to each traverse of the beam of the tube 20 across the position occupied by the spot, the spot will retain its initial brilliance. If, on the other hand, the fed back voltage is slightly less than this value the spot will slowly decay in brilliance. This decay time may be set to a desired value by suitable adjustments of the gain of the amplier 2|. On the other hand, a very weak spot created on the indicator 1 may be intensified by applying, over the regenerative network 3| and 32, signals of suflicient amplitude to cause a continually brighter spot in response to each fed-back intensifying pulse.

In systems of this character it may well happen that a transient undesired noise signal may create This signal,

as vwellfas desired signals, is fed back to the grid 6 of the 4indicator 1, and'may be intensied. To avoidthis possibility `the lower limiter 3l lis providedwhich prevents feed back ofrsignals below a certain level, and which maycorres-pond with undesired and extremely dimly lighted surfaces on the face .of Athe indicator 1.

-It is the function of the maximum limiter 22 to prevent passage to the grid 6 of regenerated voltages having greater than a predetermined magnitude, to avoid undue intensification of the face of the indicator 1. l It is the function of the gain control amplier 3l, in accordance with its gain setting, to cause either an increasing bril? lianceof lighted portions of the face of the indi-.- cator 1, to cause lighted portions to be retained unchanged despite the cessation of signal output of the radar receiver 5, or to slow down .the decay of the intensity of the face of the indicator.

It will be realized that the invention hereindescribed is of far broader application than its presently described application to P. P. I. radar indicators. Any -image produced on the face of a -cathode ray tube indicator in response to control by an intensity grid, or its equivalent in the tube, may be caused to regenerate by means of theiconoscope 20and its associated circuits. The scan -may bein rectangular, instead of in polar coordinates, or may be linear.

vTurning now to Figure 2 of the drawing, there is illustrated a pair of radar antennas, 50 and L5|-,r which are rotated continuously in synchronism by a common motor 52, so that both antennas 50 and 5i always point in the same direction during rotative movement thereof. The antenna 50 may be adapted for low angle observation, while the antenna 5l may be adapted Ffor high` angle observation, it being usually the case that an antenna which is suitable for one purpose is not suitable for the other, so that simultaneous observation of the ranges and vbearings of aircraft, some of which are ilying atlowangles and some of which are at high angles, vbecomes impossible when using a single radar equipment, the antenna of which scans in azimuth only. The radar equipments themselves may be represented by the blocks 53 and 54, respectively,- which are supplied with synchronizing pulses from a vcommon pulser 55, so that the transmissions from the two radar equipment occur simultaneously. Upon reception of a signal reected from a remote object by the radar equipment 59, an output signal is developed in the .lead 56. Upon reception of signals reflected fromremote'objects by the antenna 5i, output signals are developed in the lead 51. The output signals inleads 56 and 51 are of pulse character, duplicating substantially the shape of the transmitted pulses, as is common in pulse radar systems. The angular positions of the motor 52 are transferred to a scanning voltage generator 5,8,itowwhich is also applied signals from the puiser 55. Accordingly, the scanning generator ildevelops voltaegs which are suitable, when impressed onnthe deflectionelectrodes 59 .of a cathode ray tube indicator 6l), for causing P. P. I. scan'of the cathode ray beam of the indicator y60, across the viewing face thereof. Output signals developed in the lead 56 are applied to the intensifier .grid 6| ,of the cathode ray tube indicatorsfrthere being ,accordingly created on the face'sof thelindicator 60 a plan-position plot of the locations offremote Aobjects at relatively high angles. In the :usual application .these remote obiects be proximate aircraft.. c

A further cathode ray tube indicator 6,2 Ais pro-5; vided having deflection electrodes A63 and .an;-in-. tensi'er grid 64. Pulse signals ,developed in the output lead 51 are applied to the control electrode 64, over a manually operable switch r6.5, serving to intensify the cathode ray beam of the indicator 62. To the deflection electrodes 63 `of the indi.- cator 62 is applied scanning voltages derived from the scanning voltage generator 15B. Accordingly, there is created on the face of the indicator 2, a plan position plot .of targets .obe served by the radar 5A, and which are located at relatively high angles. It will be observed at this point that the scanning voltages applied L'to the -cathode ray tube indicators 6.0 and 62 are identical,v and accordingly that the cathode lray beams of the indicators 6U and 62 will trace out identical paths in precise synchronism.

The image created on the face of the cathode ray tube indicator 60 is impressed by suitable optical means, (not shown), on an iconoscope or image orthicon 10, having a cathode 1l, `beam deflection electrodes 12, and a light sensitive mosaic which provides an output electrode V@for the iconoscope or image orthicon 1B. TheV outl put electrode 13 is connected over an isolating amplier 1li with the input of a limiter device 15 which serves to only pass signals which have greater than a predetermined minimum value, this value being manually selectable. The out put of the limiter 15 is applied to a signal ampli fier 16 having adjustable gain, and the output of the latter is applied to a further limit oi 11, which cuts 01T the peaks of signals having values labout predetermined upper limits, the upper limits being manually selectable. The output of the upper limiter is applied over a manual-ly operable switch 18 to the intensier grid 6i of the cathode ray tube indicator 50.

The scanning voltages developed in the scanning generator 68 are applied over leads 19 to the deflection electrodes 12 of the iconoscope or image orthicon 1li so that the cathode beam of the latter traces out a path which duplicates the path traced out by the beam of the cathode ray tube indicator 5D. Accordingly, each time'that a spot is created on the face of the cathode ray tube indicator B, a corresponding signal is generated in the output electrode 13 of the iconoscope or image orthicon 10, and that output signal is applied over the isolating amplifier 15 and over a lower limiter 15, the amplifier 16 'and the upper limiter 11, to the intensier electrode 6l of the cathode ray tube indicator Sil. Ac-e cordingly, any image created on the face of the indicator 60 is regenerated by means of the iconoscope or image orthicon 10, and the associated circuits, and the image created on the face of the indicator 60 may be thus retained in.- deiinitely if desired.

Should the switch 18 be opened, however, re,- generation is prevented, and the image present on the face of the indicator 66 is permitted to decay in accordance with the natural decay rate of the flourescent material used in constructing the face of the indicator 60.

The output of the isolating amplifier 14 is fur., ther applied over a lead 8b, via a manual switch 8|, to a further lower limiter 32, any amplifier 83, and an upper limiterd, connected in cascade, and via a series connected switch to thewintensity control grid 6d of a cathode ray tube indi.- .cator 62. The lower limiter .82, the amplifier 83 and the upper limiter 8.4 may be precisely identical with the corresponding ,elementsnuma bered 15, 16 and 11, and accordingly any image present on the face of the indicator 60 may be transferred via the switch 8l, if closed, to the intensity control electrode 64 of the cathode ray tube indicator 62, so that the presentation present on face of the indicator $2v duplicates that present on the indicator 60.

With the switch 65 open, the only presentation on the face of the indicator 62 corresponds with that present on the face of the indicator 60. I-Iowever, with the switch 65 closed, two presentations are simultaneously created on the face of the indicator 62, one corresponding with the targets created in response to the high angle radar 54, and the other corresponding with the plot presented on the face of the indicator 60, and which corresponds with the plot of positions of low angle targets.

Accordingly, on the face of the indicator 62 is provided a total plot of all targets located both at 10W angles and at high angles. Any plot present on the face of the indicator 62, may be transferred opticalli7 to the photo-electric image mosaic 86 of the iconoscope or image orthicon 81, having a cathode 83 and deection electrodes 89. The leads 19 convey to the deflection electrodes B9 the necessary deiiection voltages to cause the cathode ray beam of the indicator 81 to travel a path identical with that traveled by the 'beams of the indicators 60 and 62, and by the beam of the iconoscope or image orthicon 18, and in precise synchronism therewith. Output signal developed by the photo-electric mosaic 86 may be applied over an isolating amplifier 98 to the input of the lower limiter 82, whence the signal is applied ultimately to the intensity control grid 64 of the indicator 62, serving to regenerate the image present on that indicator. Alternatively, or in addition, the image present on the mosaic 86 may be applied by the isolating amplier 96 and via the switch 8l when closed, and the lead 80, to the input of the lower limit 15, the amplier 16, the upper limiter 11, and then via the manual switch 18 to the intensity control grid 6l of the cathode ray tube indicator 60. Accordingly, any images present on the face of the indicator 62 may be transferred to the face of the indicator 68.

There is accordingly provided a system of radar indication, wherein the image presented on one cathode ray tube indicator may be transferred to another, and there retained, or permitted to decay, so that composite indications are made possible of range and bearing indications provided by a pair of radars, and selectively, either a long range or a short range plot on the same indicator.

The present system accordingly greatly enhances the utility of radar systems, at the cost of but slight increase in complexity, and without requiring modification of the basic radar systems involved.

While I have described the two specific embodiments of my invention, it will be clear that variations of the combinations disclosed, as Well as of the details thereof, may be varied without departing from the true spirit and scope of the invention,

What I claim and desire to secure by Letters Patent of the United States is:

1. In combination, a cathode ray tube indicator having electron beam generating electrodes, electron beam deflecting electrodes, an electron beam intensity control electrode, and a fluorescent screen for providing visual indications in response to variations of intensity of said electron beam, during deflection thereof, and means responsive to said visual indications for regenerating said visual indications on said cathode ray tube indicator.

2. The combination in accordance with claim 1 wherein said means for regenerating comprises a further cathode ray tube comprising a light sensitive mosaic.

3. In combination, a cathode ray tube indicator having electron beam generating electrodes, electron beam deflecting electrodes, an electron beam intensity control electrode, and a iiuorescent screen for providing visual indications in response to variations of intensity of said electron beam, means for providing simultaneous electron beam deilecting signals to said electron beam deilecting electrodes to eiTect space scanning of said electron beam and information bearing signals to said intensity control electrode to provide intensity control yof said electron beam, whereby to trace an illuminated pattern on said iiuorescent screen, and means responsive to said illuminated pattern for continually regenerating said illuminated pattern on said cathode ray tube indicator.

4. In combination, a cathode ray tube indicator having electron beam generating electrodes, electron beam deecting electrodes, an electron beam intensity control electrode, and a uorescent screen for provinding visual indications in response to variations of intensity of said electron beam, means for providing simultaneous electron beam deflecting signals to said electron beam deilecting electrodes to effect space scanning of said electron beam and information bearing signals to said intensity control electrode to provide intensity control of said electron beam, Whereby to trace an illuminated pattern on said uorescent screen, and means responsive to said illuminated pattern for generating further signals corresponding with said information bearing signals, and means for applying said furtherv signals to said intensity control electrode to regenerate said illuminated pattern.

5. In combination, a cathode ray tube indicator having electron beam generating electrodes, electron beam deflecting electrodes, an electron beam' intensity control electrode, and a fluorescent screen for providing visual indications in response to variations of intensity of said electron beam, means for providing simultaneous electron beam deflecting signals to said electron beam deflecting electrodes to effect space scanning of said electron beam and information bearing signals to said intensity control electrode to provide intensity control of said electron beam, whereby to trace an illuminated pattern on said fluorescent screen, and means comprising a further cathode ray tube responsive to said illuminated pattern for generating further signals corresponding with said information bearing signals, and means for applying said further signals to said intensity control electrode to regenerate said illuminated pattern.

6. In combination, a cathode ray tube indicator having electron beam generating electrodes, electron beam delecting electrodes, an electron beam intensity control electrode, and -a fluorescent screen for providing visual indications in response to variations of intensity of said electron beam, means for providing simultaneous electron beam deflecting signals to said electron beam deecting electrodes to effect space scanning of said electron beam and information bearing signals to said intensity control electrode to provide intensity control of said electron beam, whereby to trace an illuminated pattern on said uorescent screen, and means comprising a further cathode ray tube responive to said i1- luminated pattern for generating further signals corresponding with said information bearing signals, said further cathode ray tube comprising electron beam generating electrodes, electron beam defiecting electrodes and a photo-electric mosaic, means for applying said rst mentioned beam deecting signals to said last mentioned electron beam deiiecting electrodes, means for optically comprising said illuminated pattern on said photo-electric mosaic, and means for applying said further signals to said cathode ray tube indicator to regenerate said visual indicator.

7. In combination, a rst cathode ray tube indicator having cathode ray beam generating electrodes, beam deflection electrodes. beam intensifying electrodes, a iiuorescent screen, a second cathode ray tube indicator having cathode ray beam generating electrodes, beam deiiection electrodes, a beam intensifying electrode and a fluorescent screen, a photo-sensitive cathode ray tube having a photo-sensitive mosaic cathode ray beam generating electrodes and beam deiiection electrodes, means for applying synchronous scanning signals to said first, second and third mentioned beam deection electrodes to eiect synchronous scanning of the beams of said cathode ray tubes with respect to said fluorescent screens and said photo-sensitive mosaic, means for applying signals to said first-mentioned beam intensifying electrode to create a visual pattern on said first mentioned cathode ray screen, means for optically projecting said visual pattern on said photo-electric mosaic, and means for applying signals developed by said photo-electric mosaic in response to scanning of said third men- 16 tioned cathode ray beam to said second mexitioned beam intensifying electrode to recreate said visual image on said second mentioned uorescent screen.

8. A system for transferring a visual pattern from one cathode ray tube indicator to a second cathode ray tube indicator, comprising a scanning signal generator, means for applying signals provided by said scanning signal generator to said irst and second cathode ray tube indicator, to eiect synchronous scanning of the cathode rays of said cathode ray tube indicators, means for creating a visual pattern in said rst cathode ray tube indicator, a third cathode ray tube having a photo-electric m'osaic, means for projecting said visual image on said photo-electric mosaic, means for applying said signals provided by said scanning signal generator to said third cathode ray tube to effect synchronous scanning of the cathode rays of said second and third cathode ray tubes, and means responsive to signals developed in said photo-electric mosaic for recreating said visual pattern in said second cathode ray tube.

HYMAN HURVITZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,096,985 Von Ardenne Oct. 26, 1937 2,412,669 Bedford Dec. 17, 1946 2,412,670 Epstein Dec. 17, 1946 2,422,295 Eaton June 17, 1947 2,437,173 Rutherford Mar. 2, 1948 2,443,634 Morgan June 22, 1948 2,449,549 Byrne Sept. 21, 1948 

